This invention relates to a shift lever of a transmission for an internal combustion engine in an automobile.
Traditionally, as is well known in the art, transmissions for an internal combustion engine are classified as a manual transmission and an automatic transmission. In a manual transmission, a shift and select operations are carried out by a shift lever. The shift lever is composed of a first shift lever having a cylindrical portion and a rod-like portion which are coaxial each other, and a rod-like second shift lever having a smaller diameter than the cylindrical portion of the first shift lever. The upper end portion of the second shift lever is inserted into the cylindrical portion of the first shift lever by a predetermined length. The lower end portion of the second shift lever is fixed to a shift lever retainer provided in an extension housing of the transmission. A grip is fitted to the upper end of the rod-like portion of the first shift lever. During engine operation, the extension housing may vertically vibrate, which may cause sizzle vibration and sizzle noise of the shift lever. In the case of slow accelaration from a constant engine speed, noise may be generated by torsional vibration due to play in a driving system, or which noise is the resonance noise occurring from twist of drive line and is called "Jara" noise, and this "Jara" noise may be propagated through the shift lever into an automotive compartment.
Traditionally, in order to reduce such sizzle vibration and sizzle noise of the shift lever, and such "Jara" noise propagated through the shift lever into the automotive compartment, shock absorbing rubber rings are packed in the annular space defined by the cylindrical portion of the first shift lever and the inserted portion of the second shift lever into the cylindrical portion at the upper and lower end portions thereof. However, unless the spring constant of the shock absorbing rubbers is considerably reduced, it may be difficult to minimize the propagation of the sizzle vibration, sizzle noise and "Jara" noise of the shift lever into the automotive compartment. In this case, if the spring constant of the shock absorbing rubbers is extremely reduced, the durability of the shift lever decreases, and during the operation of the shift lever, the first shift lever is greatly bent relative to the second shift lever, thereby causing an operation feeling of the shift lever to be remarkably made worse.